While this phrase often has sexual and/or circus related meanings, it is often cited in some parts of the country as having to blow into a breathalyzer to measure blood alcohol content after a traffic stop.

Joe got pulled over and blew the clown last night, now he is in the drunk tank.

From the Randall Zwarte' Band's song, Blow the Clown: "Blow the Clown means you're going down." This is a reference to being pulled over during a traffic stop for suspicion of DUI or DWI (Driving Under the Influence).